In a method for obtaining an image through an electrophotographic printing method or an electrostatic charge development method, an electrostatic charge image formed on a photoreceptor is usually developed using toner which has been previously charged by friction, and is then fixed.
When the toner is heated during the fixing or the like, in some cases, a volatile organic compound (VOC) may be generated. There is a concern that the generation of VOC may affect the environment or the like. For this reason, in recent years, in view of health and environmental protection, reduction of the total amount of VOC (Total Volatile Organic Compound: TVOC) is required, and the reduction of TVOC (low TVOC) is required also for the resin for toner.
As a method for reducing TVOC of a binder resin, a method for prolonging decompression reaction time during production of the binder resin and removing residual monomers of the binder resin (PTL 1), and a method for adjusting the amount of a volatile component (aliphatic diol component) caused by a polyester resin (PTL 2) are proposed.
On the other hand, the polyester resin for toner generally uses a bisphenol A derivative as a composition. The bisphenol A derivative is a component that is difficult to volatize. Thus, containing a large quantity of bisphenol A derivatives is advantageous from the viewpoint of TVOC reduction, but is disadvantageous because of the influence of bisphenol A on the environmental aspect and the lowering of the resin productivity due to the poor reactivity. As an example of the polyester for toner which includes a small quantity of bisphenol A derivative components, PTL 3 is mentioned.
Furthermore, the polyester resin tends to have a low non-offset property because the polyester resin has poor peelability at the time of the fixing. Generally, a release component such as a wax is blended in the toner in order to impart peelability at the time of the fixing. However, since the polyester resin and the wax have poor compatibility, the dispersion state of the wax component is uneven. Thus, the wax rich portion and the wax poor portion are generated in the toner, and there are various problems.
PTL 4 discloses a technique of providing toner which has favorable fixing performance, non-offset property, image stability, and durability and has excellent color development and color reproducibility so as to be usable for color use, by using a polyester resin that has a high light transmittance and is polymerized in the presence of a long chain alkyl group having a specific functional group at the end. Furthermore, PTL 5 discloses a technique of providing toner which has favorable fixing performance, non-offset property, image stability, and durability, by using a binder resin composition for toner which contains a polyester resin having a constitutional unit derived from oxidized polyolefin and the oxidized polyolefin. Additionally, PTL 6 discloses a technique of providing toner which is excellent in both hot-offset resistance and electrification, by using polyester for toner obtained by performing a polycondensation reaction in the presence of the wax having a polar group.